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Old 11th July 2019, 09:20   #1  |  Link
Metal-HTPC
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How to encode 720p, 25fps BD compliant ?

hello,

when I encode 720p HD sources with 29,97 to BD compilant 720p sources I usually use changefps(59.94) in Avisynth and make a 720p59.94 x264 encode.

This time time I have a 25fps 720p HD source so I want to go for the 720p50 specification but somehow changefps(50.00) doesn't work. I get an error and don't understand why this is a wrong divisor?
There is also the possibility to not use the avisynth fps command and just go for a
720p25, which (according to http://www.x264bluray.com/home/720p-encoding) doubles the framerate with the "--pulldown double preset".
The encode works fine but plays with 50% more speed which is totally senseless.

Any advice is appreciated
thanks
regards
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Old 11th July 2019, 15:05   #2  |  Link
junah
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Does it even have 50 original frames?
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Old 11th July 2019, 16:29   #3  |  Link
Sharc
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What is the (avisynth) error you are getting?
--pulldown double encode with wrong playback speed: Do you watch the .264 raw stream? If so, mux it into a container (.mkv, .mp4, .m2ts) and set the framerate to 50fps

Upload a sample (few seconds duration) of your source so someone can take a look.

Last edited by Sharc; 11th July 2019 at 16:53.
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Old 11th July 2019, 18:56   #4  |  Link
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Quote:
Originally Posted by Sharc View Post
--pulldown double encode with wrong playback speed:
Is it a bug un x264 ? In that case, it has to be reported.
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Old 11th July 2019, 21:32   #5  |  Link
Sharc
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Quote:
Originally Posted by jpsdr View Post
Is it a bug un x264 ? In that case, it has to be reported.
Not as I know. The OP might however have a problem with the player, hence my recommendation to mux the .264 video stream into a container for playback. Just a thought.
Btw. exactly the same topic is discussed in the videohelp forum as well …….
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Old 11th July 2019, 21:58   #6  |  Link
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25p should be accepted and it shouldn't speed the video up by 50%.
Encode a few minutes like so by only using an indexer:

x264 --bitrate 25000 --preset veryslow --tune film --bluray-compat --vbv-maxrate 40000 --vbv-bufsize 30000 --level 4.1 --keyint 25 --open-gop --slices 4 --pulldown double --colorprim "bt709" --transfer "bt709" --colormatrix "bt709" --sar 1:1 --pass 1 -o "out.264" "AVS_Script.avs"

x264 --bitrate 25000 --preset veryslow --tune film --bluray-compat --vbv-maxrate 40000 --vbv-bufsize 30000 --level 4.1 --keyint 25 --open-gop --slices 4 --pulldown double --colorprim "bt709" --transfer "bt709" --colormatrix "bt709" --sar 1:1 --pass 2 -o "out.264" "AVS_Script.avs"

Otherwise, with Avisynth you can do something like:

Code:
ConvertFPS(50)
assumeTFF()
separatefields()
selectevery(4,0,3)
weave()
and then encode everything as 25i:

x264 --bitrate 25000 --preset veryslow --tune film --bluray-compat --vbv-maxrate 40000 --vbv-bufsize 30000 --level 4.1 --keyint 25 --open-gop --slices 4 --tff --colorprim "bt709" --transfer "bt709" --colormatrix "bt709" --sar 1:1 --pass 1 -o "out.264" "AVS_Script.avs"

x264 --bitrate 25000 --preset veryslow --tune film --bluray-compat --vbv-maxrate 40000 --vbv-bufsize 30000 --level 4.1 --keyint 25 --open-gop --slices 4 --tff --colorprim "bt709" --transfer "bt709" --colormatrix "bt709" --sar 1:1 --pass 2 -o "out.264" "AVS_Script.avs"


Last but not least, you can try 50p by using FFMpegSource2 as indexer and setting fpsnum 50000, fpsden 1000 like so:

Code:
FFMpegSource2("source.m2ts", fpsnum=50000, fpsden=1000, atrack=-1)
and then encode everything as 50p:

x264 --bitrate 25000 --preset veryslow --tune film --bluray-compat --vbv-maxrate 40000 --vbv-bufsize 30000 --level 4.1 --keyint 50 --open-gop --slices 4 --colorprim "bt709" --transfer "bt709" --colormatrix "bt709" --sar 1:1 --pass 1 -o "out.264" "AVS_Script.avs"

x264 --bitrate 25000 --preset veryslow --tune film --bluray-compat --vbv-maxrate 40000 --vbv-bufsize 30000 --level 4.1 --keyint 50 --open-gop --slices 4 --colorprim "bt709" --transfer "bt709" --colormatrix "bt709" --sar 1:1 --pass 2 -o "out.264" "AVS_Script.avs"
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Last edited by FranceBB; 11th July 2019 at 22:01.
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Old 11th July 2019, 22:24   #7  |  Link
Sharc
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Quote:
Originally Posted by FranceBB View Post
. and then encode everything as 25i: ...
720 must be progressive for Blu-ray compliance.
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Old 12th July 2019, 02:37   #8  |  Link
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Ah, right, right, only 1080i is compliant so he would have to upscale as well... possibly with Spline36 or Spline64Resize in that case... (or NNEDI + Spline).
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Old 12th July 2019, 10:03   #9  |  Link
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It doesn't matter if I chose "changefps(50.00)" "changefps("pal_double") or "changefps(50, 1)" it always leads to the error "error: Evaluate: System exception - Integer Divide by Zero"
The commandline I used was
Quote:
--bluray-compat --level 4.1 --keyint 50 --sar 1:1 --slices 4 --vbv-bufsize 30000 --vbv-maxrate 40000 --b-pyramid none --weightp 0 --colorprim bt709 --transfer bt709 --colormatrix bt709 --merange 24
according to http://www.x264bluray.com/home/720p-encoding the blu-ray specification for 720p 25fps blu-rays has to be done using the "--pulldown double" command which makes 50 out of the 25fps. The problem is that this command doesn't work here because it doubles the playback speed. If a 720p 25fps blu ray without the framerate duplication is supported as well then I give it a try. Thanks so far guys and a good weekend
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Old 12th July 2019, 11:45   #10  |  Link
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Doubles the playback speed on what software / hardware?
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Old 12th July 2019, 21:23   #11  |  Link
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Quote:
Originally Posted by Metal-HTPC View Post
It doesn't matter if I chose "changefps(50.00)" "changefps("pal_double") or "changefps(50, 1)" it always leads to the error "error: Evaluate: System exception - Integer Divide by Zero"
Can't you just let the indexer duplicate frames to 50fps progressive?

Code:
FFMpegSource2("source.m2ts", fpsnum=50000, fpsden=1000, atrack=-1)
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Old 13th July 2019, 05:04   #12  |  Link
huhn
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the normal none BD spec doesn't have 25p at all it is either 720p50 or 1080i50 and well yeah 1440x1080i50. which the tp well knows.

is 720 uspcale to 1080 an option for you?
if yes all you need is now set the fake-interlaced flag for x264 and you are done.

Quote:
error: Evaluate: System exception - Integer Divide by Zero
can you just as a test try this:

assumeFPS(25)
changeFPS(50)
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